ISL6323EVAL1Z Intersil, ISL6323EVAL1Z Datasheet - Page 27

• Manufacturer Part Number: ISL6323EVAL1Z
• Description: EVAL BOARD 1 FOR ISL6323
• Manufacturer: Intersil

Specifications of ISL6323EVAL1Z

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CASE 2
In Case 2, the DC voltage across the North Bridge inductor
at full load is greater than the DC voltage across a single
phase of the Core regulator while at full load. Here, the DC
voltage across the North Bridge inductor must be scaled
down to match the DC voltage across the Core inductors,
which will be impressed across the ISEN pins without any
gain. So, the R
left unpopulated and K = 1.
Where: K = 1
K
------------------------- -
DCR
I
R
K
---------------------
DCR
R
K
6. Calculate the values for R
NB MAX
1. Choose a capacitor value for the Core RC filter. A 0.1µF
2. Calculate the value for resistor R
4. Using Equation 40 (also derived from Equation 20),
5. Choose a capacitor value for the North Bridge RC filter. A
6. Calculate the values for R
3. Calculate the value for the R
1
SET
L
L
=
=
Core
=
Core
NB
Equations 35 and 36 will allow for their computation.
capacitor is a recommended starting point.
(Derived from Equation 20).
calculate the value of K for the North bridge regulator.
0.1µF capacitor is a recommended starting point.
Equations 41 and 42 will allow for their computation.
----------------------------------------------
R
------------------------------------ -
R
Core
--------- - R
400
NB
3
1
1 NB
=
Core
=
⋅
R
400
--------- -
=
⋅
R
DCR
3
2 NB
=
----------------------------------------------- -
DCR
+
2
------------------------------------ - C
R
R
SET
Core
+
R
1 NB
---------------------------------------------- C
R
1 NB
R
⋅
R
2 NB
NB
DCR
-------------------------------------- -
1
1
2
Core
Core
2
Core
L
⋅
N 100μA
Core
+
resistor for the Core inductor RC filters is
---------------------
DCR
Core
⋅
>
⋅
R
R
CORE
I
-------------------------- DCR
Core
2 NB
⋅
2 NB
+
1
⋅
C
R
R
NB
Core
N
2
2
MAX
Core
⋅
Core
⋅
⋅
K
------------------------------------------------------------------------- -
I
OCP
NB
⋅
⋅
⎛
⎜
⎝
27
⋅
I
1
1
OCP
SET
NB
Core
and R
and R
+
Core
CORE
resistor using Equation 39:
100μA
---------------------------- -
2 L
V
1
IN
⋅
2
2
:
NB
–
for North Bridge.
for Core.
+
V
V
-------------------------------------------- -
NB
⋅
2 L
f
IN
S
⋅
⋅
–
V
-----------
CORE
V
N V
NB
IN
⋅
CORE
(EQ. 40)
(EQ. 35)
(EQ. 36)
(EQ. 38)
(EQ. 41)
(EQ. 42)
(EQ. 39)
(EQ. 37)
⋅
f
S
⋅
V
------------------- -
ISL6323
CORE
V
IN
⎞
⎟
⎠
CASE 3
In Case 3, the DC voltage across the North Bridge inductor
at full load is equal to the DC voltage across a single phase
of the Core regulator while at full load. Here, the full scale
DC inductor voltages for both North Bridge and Core will be
impressed across the ISEN pins without any gain. So, the R
resistors for the Core and North Bridge inductor RC filters
are left unpopulated and K = 1 for both regulators.
For this Case, it is recommended that the overcurrent trip
point for the North Bridge regulator be equal to the
overcurrent trip point for the Core regulator divided by the
number of core phases.
Where: K = 1
NOTE: The values of R
less than 80kΩ. For all of the 3 previous cases, if the
calculated value of R
OCP trip point needs to be increased or the inductor must be
changed to an inductor with higher DCR. If the R
is greater than 80kΩ, then a value of R
80kΩ must be chosen and a resistor divider across both
North Bridge and Core inductors must be set up with proper
gain. This gain will represent the variable “K” in all equations.
It is also very important that the R
between the RSET pin and the VCC pin of the ISL6323.
I
R
R
R
I
NB
1. Choose a capacitor value for the North Bridge RC filter. A
2. Calculate the value for the North Bridge resistor R
3. Choose a capacitor value for the Core RC filter. A 0.1µF
4. Calculate the value for the Core resistor R
5. Calculate the value for the R
6. Calculate the OCP trip point for the North Bridge
OCP NB
1
1
SET
NB
Core
MAX
0.1µF capacitor is a recommended starting point.
capacitor is a recommended starting point.
regulator using equation 47. If the OCP trip point is higher
than desired, then the component values must be
recalculated utilizing Case 1. If the OCP trip point is lower
than desired, then the component values must be
recalculated utilizing Case 2.
=
=
=
⋅
------------------------------------- -
DCR
=
DCR
400
--------- -
3
----------------------------------------------- -
DCR
100μA
⋅
L
NB
NB
DCR
-------------------------------------- -
NB
Core
L
N 100μA
⋅
Core
=
C
⋅
⋅
CORE
---------------------
DCR
NB
I
-------------------------- DCR
⋅
Core
C
SET
1
Core
SET
N
NB
MAX
⋅
is less than 20kΩ, then either the
K
⋅
⋅
⎛
⎝
must be greater than 20kΩ and
⎛
⎜
⎝
--------- - R
400
⋅
I
3
OCP
SET
⋅
SET
CORE
Core
resistor using Equation 46:
SET
resistor be tied
SET
⎞
⎠
+
+
V
-------------------------------------------- -
---------------------------- -
2 L
V
that is less than
2 L
IN
IN
⋅
⋅
NB
–
1
–
:
CORE
N V
V
SET
October 21, 2008
NB
⋅
⋅
f
S
CORE
(EQ. 44)
(EQ. 45)
(EQ. 46)
⋅
(EQ. 47)
resistor
(EQ. 43)
⋅
V
-----------
FN9278.4
V
1
f
NB
S
:
IN
⋅
2
V
------------------- -
CORE
V
IN
⎞
⎟
⎠